1. Field of the Invention
This invention relates to the field of electrodes that are used in gas tungsten arc (GTA) welding and plasma arc (PA) welding, and in particular to an improved non-consumable welding electrode used primarily in gas tungsten arc and plasma arc welding which includes the use of improved chemical compositions of the electrode for improving the welding properties for superior welding capability and controllability in the welding processes.
2. Description of Related Art
Gas tungsten arc welding and plasma arc welding utilize an electrical arc to accomplish the welding processes. Typically in GTA or plasma arc welding the primary electrode consists of elemental tungsten usually with one to two percent thorium oxide or in an alternative embodiment 0.15%-0.40% zirconium oxide. Some of the objectives for the most efficient gas tungsten arc welding and plasma arc welding are to obtain high currents for increasing welding power for the particular sized welding electrode and voltage used, a stable arc, reliable starting of the arc, and cooling of the electrode because of the tremendous heat generated during the process. In pursuing these objectives various references have been shown in the prior art. U.S. Pat. No. 2,922,028 issued to Butler et al. Jan. 19, 1960 shows electric arc electrodes using 2% thoriated tungsten as an electrode. U.S. Pat. No. 3,198,932 issued to Wetherly, Aug. 3, 1965, discloses a plurality of insert tips useful in cutting with a reactive gas as the arc gas. U.S. Pat. No. 3,231,332, issued to Jones et al., Jan. 25, 1966, discloses use of an electrode having an outer layer consisting of pure tungsten or tungsten containing one or more additives such as alumina and potassium silicate. U.S. Pat. No. 3,976,853 issued to Trattner et al., issued Aug. 24, 1976, discloses an electrode having a tip bore filled with a powdered high melting electron emission material centered in situ.
The present invention has been determined to provide a welding electrode that has an electron emission capability superior to conventional GTA and
thoriated tungsten and zirconated tungsten electrodes. In specific configurations provided in the present invention, the invention also possesses superior electrical and thermal conductivity properties. By providing an electrode having a lower thermionic work function as compared with prior art GTA and PA electrodes, the electrode in accordance with the present invention requires less energy to emit electrons resulting in higher welding efficiencies.